An optical disk playback device for playing back an optical disk, such as a CD-ROM, reads contents information in a program area recorded in a TOC area on the optical disk, and reads information about music, an image, or the like recorded in the program area on the basis of the contents information to play back the information. Such an optical disk playback device performs the same operation on a write-once type optical disk, such as a CD-R, and a re-recordable optical disk, such as a CD-RW.
By the way, a problem occurring in a mastering process for commercial disks, a problem occurring when the user writes data into a writable type disk, an error occurring at a time of TOC reading, or the like may cause a difference between the contents information ready by a drive (a control microcomputer) and the address of the actually-acquired program area. In this case, there arises a problem that when performing a search for a track start point on the basis of the contents information of the TOC, a track position which is different from the actual one is searched for and, for example, a playback is started from some midpoint of a musical piece or a flickering screen display is produced.
There is known a technology of, in order to solve this problem, judging whether playback equipment has succeeded or failed in reading out the contents information of an optical disk on the basis of the length of time required to read out the contents information (for example, refer to patent reference 1).    [Patent reference 1] JP,2003-272348,A
According to the technology disclosed by the above-mentioned patent reference 1, because correct contents information can be acquired from the TOC of an optical disk before the playback equipment starts a playback of data, the playback equipment can be prevented from being unable to play back the data due to incorrect contents information.
However, because the playback equipment repeats a process of acquiring the contents information until it can acquire the correct contents information from the optical disk, even if the reliability of the data playback of the optical disk can be improved, there may be a case in which the playback equipment falls into a loop and cannot terminate normally depending on the cause of an occurring error, and therefore cannot play back the data.
The present invention is made in order to solve the above-mentioned problems, and it is therefore an object of the present invention to provide an optical disk playback device which, when receiving a search request, performs a track search according to contents information, compares a current track start point position at a time after performing the track search with a target track start point position, and, when the comparison result shows that they differ from each other, sets up a new target track start point position by performing a predetermined arithmetic operation, and which, as a result, can find out a correct track start point position promptly and can start a playback of data.